/*
 * Copyright (c) 2011-2014 Pivotal Software, Inc.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.camunda.bpm.extension.reactor.projectreactor.support;

import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * A thread factory that creates named daemon threads. Each thread created by this class
 * will have a different name due to a count of the number of threads  created thus far
 * being included in the name of each thread. This count is held statically to ensure
 * different thread names across different instances of this class.
 *
 * @author Jon Brisbin
 * @author Stephane Maldini
 * @see Thread#setDaemon(boolean)
 * @see Thread#setName(String)
 */
public class NamedDaemonThreadFactory implements ThreadFactory {

  private static final AtomicInteger COUNTER = new AtomicInteger(0);

  private final String prefix;
  private final boolean daemon;
  private final ClassLoader contextClassLoader;
  private final Thread.UncaughtExceptionHandler uncaughtExceptionHandler;

  /**
   * Creates a new thread factory that will name its threads &lt;prefix&gt;-&lt;n&gt;, where
   * &lt;prefix&gt; is the given {@code prefix} and &lt;n&gt; is the count of threads
   * created thus far by this class.
   *
   * @param prefix The thread name prefix
   */
  public NamedDaemonThreadFactory(String prefix) {
    this(prefix, new ClassLoader(Thread.currentThread().getContextClassLoader()) {
    });
  }

  /**
   * Creates a new thread factory that will name its threads &lt;prefix&gt;-&lt;n&gt;, where
   * &lt;prefix&gt; is the given {@code prefix} and &lt;n&gt; is the count of threads
   * created thus far by this class. If the contextClassLoader parameter is not null it will assign it to the forged
   * Thread
   *
   * @param prefix             The thread name prefix
   * @param contextClassLoader An optional classLoader to assign to thread
   */
  public NamedDaemonThreadFactory(String prefix, ClassLoader contextClassLoader) {
    this(prefix, contextClassLoader, null, true);
  }

  public NamedDaemonThreadFactory(String prefix,
                                  ClassLoader contextClassLoader,
                                  Thread.UncaughtExceptionHandler uncaughtExceptionHandler,
                                  boolean daemon
  ) {
    this.prefix = prefix;
    this.daemon = daemon;
    this.contextClassLoader = contextClassLoader;
    this.uncaughtExceptionHandler = uncaughtExceptionHandler;
  }

  @Override
  public Thread newThread(Runnable runnable) {
    Thread t = new Thread(runnable);
    t.setName(prefix + "-" + COUNTER.incrementAndGet());
    t.setDaemon(daemon);
    if (contextClassLoader != null) {
      t.setContextClassLoader(contextClassLoader);
    }
    if (null != uncaughtExceptionHandler) {
      t.setUncaughtExceptionHandler(uncaughtExceptionHandler);
    }
    return t;
  }

}
